Ignition system



April 15, 1969 W. D. CLYBORNE ETAL IGNITION SYSTEM Original Filed Jan 4,1966 INVENTOR. (J/Lu: D. Grace/w! BY Ham 5. C2 YJOEN! Maw Arron/ KUnited States Patent US. Cl. 123-1465 8 Claims ABSTRACT OF THEDISCLOSURE Electro-optical circuit interrupter mechanism for use withthe distributor of an internal combustion engine to replace thecustomary distributor points as the means for converting thesteady-state D.C. battery current into a pulsating D.C. current enablingthe primary winding of the ignition transformer to be energized thereby.The interrupter mechanism includes a light source located exteriorly ofthe distributor casing, a ph-otoresponsive sensor located within thecasing, a light pipe through which light is conducted from the source tothe sensor, an apertureequipped interrupter disc rotatably driven by thedistributor shaft and located between the sensor and light pipe tocyclically interrupt the transmission of light therebetween and aswitching circuit responsive to the sensor for cyclically interruptingthe primary circuit of the ignition transformer in correspondence withchanges in the condition of the sensor.

This application is a continuation of Ser. No. 518,576, filed Jan. 4,1966.

This invention relates to an ignition system adapted for use withinternal combustion engines and the like; and it relates moreparticularly to that portion of such ignition system through which thecustomarily provided, steadystate D.C. battery current is converted intoa pulsating D.C. current to enable a high voltage to be developed fromthe low battery voltage in a step-up transformer.

Conversion of the low value, direct current voltage usually provided bya six or twelve volt storage battery, to the much higher value voltagenecessary to create an arc across the spaced terminals of each sparkplug or sparking device used in an internal combustion engine has longbeen accomplished by means of mechanical breaker points interposed inthe primary circuit of a step-up transformer to repetitively completeand interrupt such circuit and thereby effectively change thesteady-state battery current supplied thereto into a pulsating currenteffective to energize the secondary winding of the transformer.conventionally, the breaker points are located within the distributorcasing of such engine which enables a single engine-driven shaft toangularly displace the rotor member of the distributor (which rotormember successively connects in turn each of the various sparkingdevices to the secondary winding of the transformer) and to open andclose the breaker points in timed relation therewith.

It is well known that such breaker points which mechanically open andclose the circuit therethrough are subject to considerable wear andfatigue and, therefore, require frequent cleaning, adjusting andreplacement. Moreover, since at least one of the breaker points is amovable component, the mechanical inertia inherent in the reciprocatorydisplacement thereof causes considerable inaccuracy in the timing of theignition system, especially at higher engine speeds. Additionally, thereis a bounce or rebound factor involved in the movable point contactclosing against the stationary contact which also interferes adverselywith high quality engine performance especially at higher speeds.

As a consequence of these characteristic difliculties and limitationsinherent in mechanical breaker points, efforts have been made toeliminate the same, and an exemplary instance thereof is Berdine et a1.Patent No. 2,984,695 wherein the mechanical breaker points can beselectively replaced by an electro-optical system in which a beam oflight is directed toward a photoelectric cell and the light beamrepetitively interrupted to cyclically and alternately energize andde-energize the photoelectric cell, which alternate conditions thereofare used to complete and interrupt the circuit through the primarywinding of a step-up transformer just as in the case of the mechanicalbreaker points.

It has been found that the electro-optical system disclosed in suchpatent has not been wholly satisfactory for commercial use because of asomewhat limited period of dependable accuracy and general reliability.The present invention constitutes an improved ignition system of thegeneral type described in such Patent No. 2,984,695; and in thisrespect, has a significantly greater life expectancy throughout whichreliable and accurate performance is attained. Further, the system ofthe present invention affords rapid and accurate triggering of theignition system; it has an exceedingly fast response time-in thenanosecond range (i.e., 10- second); it permits the spark gap of eachengine spark plug or sparking device to be much greater than in the pastwith the result that a longer, flatter and hotter spark is providedwhich enables engine fuel to be burned more efficiently and therebyresults in the development of greater engine horsepower; and it affordsgreater accuracy of control over the duration of each sparking periodthroughout the: entire operating range of the engine.

An ignition system comprising the present invention includes adistributor which may be substantially conventional except that theusual mechanical breaker points are completely omitted and anelectro-optical circuit interrupter mechanism substituted therefor. Suchelectro-optical system includes a source of radiant energy which may bein the form of a light or electric lamp located exteriorly of thedistributor casing, a sensor located within the casing and responsive tothe receipt of energy from such source, and an energy conductorextending through the casing and terminating at one end adjacent theenergy source and terminating adjacent its other end in spaced relationwith the sensor. Also mounted within the distributor casing intermediatethe sensor and adjacent end of the energy conductor is an interrupterrotated by the enginedriven distributor shaft and operative alternatelyand repetitively to permit and obstruct the transmission of radiantenergy from the conductor thereof to the sensor. Responsive to thesensor and controlled thereby is a switching circuit coordinatelyoperative to complete and interrupt cyclically the primary circuit ofthe ignition transformer in accordance with the alternate conditions ofthe sensor.

An embodiment of the invention is illustrated in the accompanyingdrawing in which:

FIGURE 1 is a schematic view of an engine ignition system embodying thepresent invention; and

FIGURE 2 is a vertical sectional view of a distributor forming a part ofsuch system and made in accordance with the present invention.

The ignition system shown in the drawing is suitable for use with aninternal combustion engine as, for example, the usual gasoline engineemployed as the power plant in automobiles and other land vehicles, inmarine and airborne vehicles, etc. The system to a great extent isconventional and includes the customary source of direct current powersuch as the storage battery 10 shown in FIGURE 1. As is well known, suchbattery ordinarily defines a six or twelve volt D.C. source, but asrespects the present invention, any voltage value can be provided.

The system further includes a distributor, generally shown in FIGURE 2and denoted in its entirety with the numeral 11. The distributor itselfis in many respects conventional and includes a casing 12 having aremovable cap 13. The cap is provided with a high voltage terminal 14connected by a conductor 15 to one side of the secondary winding 16 of atransformer 17. As in the usual case, the transformer 17 shown is anauto-transformer and, accordingly, the other end of the secondarywinding 16 is grounded in common with one end of the primary Winding 18.

The distributor 11 is also provided with a plurality of angularly spacedcontacts 19, as shown in FIGURE 2, adapted to be connected by aplurality of respectively associated conductors 20 (only one of which isshown) to conventional sparking devices or spark plugs 21. In FIGURE 1,only one such contact 19, conductor 20 and sparking device 21 areshownit being understood that there will be a separate contact,conductor and sparking device for each cylinder of the engine, usuallynumbering 4, 6 or 8 in the automotive environment. Since the contactsare identical, each is identified in FIGURE 2 with the numeral 19, andas shown in FIGURE 1, one side of each sparking device 21 is grounded,usually through the engine and vehicle chassis.

The casing 12 is provided centrally along the bottom closure wallthereof with a hub or collar 22 that provides a mounting for a sleevebearing 23. Extending upwardly through the bearing 23 is a hollowtubular shaft 24 co axially and rotatably passing therethrough adistributor shaft 25 adapted to be driven by the engine through asuitable gear train (not shown). Adjacent its upper end, the distributorshaft 25 has a rotor 26 mounted thereon which rotates therewith, andrelative angular displacements between the shaft and rotor are preventedin any suitable manner, as by means of flattened contiguous surfaceareas respectively provided by the shaft and rotor and which also serveas a polarizing means to cause the rotor to be mounted upon the shaft ina predetermined angular position with respect thereto. This latterfeature is necessary since the rotor is removable and the timing of theengine would be destroyed if the precise angular relationship betweenthe shaft and rotor were not maintained. As in the usual manner, therotor 26 is formed of an insulated material but is equipped with aconductor or conductive strip 27, one end of which is in continuousengagement with the high voltage terminal 14 and the other end of whichis adapted to selectively engage the successive contacts 19 as the rotoris angularly displaced by the shaft 25.

Located within the casing 12 is a timing plate 28 equipped with a hub ordepending collar 29 circumjacent the hollow shaft 24 and pinned orotherwise secured thereto. The timing plate 28 is adapted to beangularly adjusted with respect to the axis of rotation of thedistributor shaft 25 for the purpose of advancing the spark or time ofspark occurrence as engine speed increases. Usually, such adjustment isaccomplished automatically, as by connection of the plate 28 to an armor lever 30 that extends through the casing 12 and into operativeassociation with a conventional vacuum motor 31 adapted to be connectedto the intake manifold of the associated engine.

Secured to the plate 28 is a mounting block 32 formed of a good heatconducting material such as aluminum, and the mounting block may befixedly secured to the plate in any suitable manner, such as by means ofthe cap screws shown. The mounting block 32 is provided with a recess 33therein into which depends the terminals of a sensor 34 removablysecured to the mounting block by cap screws or other appropriatefastener structure. The sensor 34 is characterized by being responsiveto the receipt thereby of radiant energy; and in the particular formshown, the sensor is responsive to radiant energy in the visiblespectrum, such as that provided by a conventional incandescent lamp.

Also, fixedly secured to the plate 28 by cap screws or other suitablemeans is a support 35 that may be formed of aluminum for heatdissipating purposes, and the support 35 extends upwardly from the plate28 and is provided adjacent its upper end with a laterally extendingcollar 36 that projects through an opening provided therefor in the sideWall of the casing 12. At its outer end exteriorly of the casing, thecollar 36 is equipped with threads adapted to receive thereon a socket37 for an incandescent lamp 38. The lamp 38 may be a conventional lightbulb having, for example, a rating of 6 to 12 volts; and, in the usualmanner, one terminal of the lamp 38 is grounded through the casingthereof and socket 37, and its other terminal is connected to aconductor 39.

The collar 36 of the support 35 is hollow, and mounted within the collaris a radiant energy conductor 40 in the form of an elongated rodterminating at one end adjacent the bulb 38 and terminating at its otherend a spaced distance from the sensor 34. The rod 40 is adapted totrans- Init radiant energy from the source thereof defined by the lamp38, and in the form shown, the conductor transmits light therealong andmay be a bar of transparent plastic sold under the trademark Lucitehaving all of the longitudinal surfaces thereof rounded since lightenergy has a tendency to escape at any sharp edge thereof. The conductor40 is fixedly secured to the support 35 by a releasable clamp 41 whichpermits adjustment of the axial position of the rod for alignment of theinner end thereof with the aperture or photosensitive surface of thesensor 34. The conductor 40 has a concave outer end portion 42conforming generally to the configuration of the bulb 38 so as topartially nest the same therein, and the spring component of the socket37 tends to resiliently bias the bulb against such arcuate end of theconductor. At its inner end, the conductor 40 is turned downwardly andtraverses an arc of approximately to effect alignment of the inner endthereof with the sensor 34.

Interposed between the sensor 34 and the adjacent and switch 48. Theresistance 47 simply reduces the batalong alternate areas respectivelyadapted to pass or transmit energy therethrough and to obstruct orprevent the transmission of energy from the conductor to the sensor. Inthe form shown, the interrupter 43 is a circular disc formed of anopaque material such as aluminum, and provided at angularly spaceddistances therealong with a plurality of apertures 44. Thus, eachaperture 44 defines such energy-transmitting area and the interposedportions of the opaque disc 43 define the energy-obstructing areas. Thedisc 43 is equipped with a collar 45 circumjacent the distributor shaft25 and it is secured thereto by a key and keyway composition 46 whichcauses the interrupter to rotate in enforced synchronism with the shaft.Evidently, there will be an aperture 44 for each contact 19 and,therefore, for each sparking device 21 of the associated engine.

Referring to FIGURE 1, the lamp 38 is connected to the battery 10through a voltage dropping resistance 47 and switch 48. The resistance47 simply reduces the battery potential to that suitable for operationof the lamp 38, and the switch 48 may comprise a part of the ignitionswitch for the associated engine. Not only is the switch operative tointerrupt the circuit to the light source 38, but it also interrupts thecircuit to the entire ignition system illustrated. The point ofconnection of the resistance 47 with the switch 48 is denoted foridentification with the numeral 49, and connected thereto is one side ofa resistance 52 serving as a current limiter for the sensor 34.

The sensor 34 is a solid state device, and in the form shown, is aphotosensitive NPN transistor having its emitter and collectorelectrodes connected externally in the circuit. In this respect, theemitter electrode is connected to a circuit 53 and supplies inputsignals thereto, and the collector electrode is connected to theresistance 52 and, therethrough, to the power source 10. Thephotosensitive transistor shown functions as a light sensitive switchfor the circuit 53, and it may be any one of a number of commerciallyavailable devices, as, for example, an FPM-100 phototransistor suppliedby Fairchild Semiconductor of San Rafael, Calif.

The signal developed by the transistor 34 is delivered to the circuit 53which is a switching or chopping type circuit operative in effect tomake and break the energizing circuit of the transformer 17 inaccordance with the condition of the transistor 34. That is to say,whether such energizing circuit is actually completed or interruptedwill depend upon the specific circuit 53 employed, but in any event thecircuit 53 is operative to effect energization and de-energization ofthe transformer in accordance with the state of the sensor as it isswitched between the energized or current conductive and de-energized ornonconductive conditions thereof. Any one of a number of circuits may beemployed and a typical example is an amplifier circuit known as aTransistorized Capacitor Discharge Ignition System which is describedunder such title in the June 1965 edition of Popular Electronics, page43. Such circuit is also illustrated in detail along with componentvalues in FIGURE 3 of this article, and a commercial embodiment of thecircuit can be obtained from various sources such as the Sydmur Companyof Brooklyn, N.Y.

Operation of an engine with which the ignition system is associated isconventional in all respects as concerns the general function of theengine and, accordingly, when the engine is energized the distributorshaft 25 will be rotated and the rotor 26 and interrupter 43 will berotated therewith. As the rotor is driven by the shaft 25, thesuccessive angularly spaced contact 19 will be connected in turnone-by-one with the high voltage terminal 14, whereupon the voltagecyclically present thereat will be applied to the associated sparkingdevice 21 to cause the usual arcto occur across the spaced apartterminals thereof. Consequently, the compressed fuel within theassociated cylinder will be ignited by such spark or arc in the usualmanner.

There is an aperture or opening 44 in the interrupter 43 for each of theengine cylinders and such openings may have various configurations and,for example, can be circular, a rectangular slot, fan-shaped, etc.Irrespective of the particular shape of such openings, in the usual casethe edges thereof will be relatively sharp so as to effect a rapidtransition between the light-transmitting and light-obstructingconditions as the interrupter 43 rotates. In any event the apertures 44are relatively small, and in the illustration of FIGURE 2, it will benoted that the apertures are slightly smaller in radial extent than thediameter of the light conductor 40 which, in a typical installation, hasa diameter of about 7 of an inch. In the embodiment of the inventionillustrated, the terminal surface of the light conductor 40 issubstantially normal to a vertical axis through the light receivingsurface of the sensor 34. Deviation from this condition of normalcy istolerable, but depending upon the amount of light developed by the lamp38, an angle of incidence of about or less is most desirable.

The sensor or photosensitive transistor 34 is essentially reverselybiased with substantially no light incident on the photosensitiveelement thereof and, accordingly, there will be substantially no flow ofcurrent through the sensor during such dark or no-light condition. Thiscondition of the sensor will obtain Whenever a space between adjacentapertures 44 is in substantial alignment with the sensor and adjacentend of the light conductor 40. Accordingly, substantially no inputsignal will be delivered to the circuit 53 during such period and, as aresult, the primary circuit of the transformer 17 will be interrupted atthis time. This condition is equivalent to that present in aconventional engine distributor and ignition system when the mechanicalpoints thereof are separated.

On the other hand, each time an aperture 44 is displaced into alignmentwith the sensor 34, the sensor will be energized by the light thenincidentthereon and current will flow through the load resistance 52whereupon an input signal will be transmitted to the circuit 53 causingthe same to close the primary circuit through the transformer 17. Thiscondition is equivalent to that present in a conventional enginedistributor and ignition system when the mechanical points thereof areclosed. With the transformer energized, a secondary voltage will beinduced therein effective to cause one of the sparking devices 21 to beenergized.

As the distributor shaft 25 drivingly rotates the interrupter 43, theangularly spaced apertures 44 provided thereby are moved successivelyinto alignment with the light receiving surface of the sensor 34 and theadjacent end of the light conductor 40. Since the lamp 38 is energizedcontinuously, the light developed thereat is transmitted to and will becontinuously present at the inner end of the conductor 40, which innerend is in alignment with the sensor 34. As explained heretofore, therotor 26 and interrupter 43 are both fixedly mounted upon thedistributor shaft 25 so as to rotate simultaneously therewith. Further,the various apertures 44 of the interrupter 43 are located andpositioned with respect to the conductor 27 and the rotor 26, and alsowith respect to the location of the various terminals 19, so that anaperture 44 is substantially in alignment with the sensor 34- wheneverthe conductive strip 27 is in substantial engagement with a contact 19.As a consequence of such interrelationship of the sensor 34, lightconductor 40 and apertures 44 with the terminals 19 and conductive strip27, a secondary voltage is developed by the transformer 17 fortransmission to a sparking device 21 each time the conductive strip 27is in electrical engagement with a contact 19.

The precise time relationship, however, between the engagement of theconductive strip 27 with a terminal 19 and the location of the sensor 34with respect to an aperture 44 will depend upon the engine speed andwhether the engine is accelerating or decelerating. In this respect, thetiming plate 28 will be advanced or retarded automatically by the rod 30and vacuum motor 31 in a completely conventional manner in accordancewith the operating condition of the engine and, more particularly, thetiming will be advanced slightly as the engine speed is increased. Thus,whenever the timing plate 28 is angularly displaced with respect to theaxis of the shaft 25, the sensor 34 will be displaced therewith and thelight conductor 40 will be similarly displaced therewith since both thesensor and light conductor are fixedly carried by the plate 28 throughthe mounting block 32 and support 35. Consequently, each arcing of asparking device 21 can be made to occur more quickly if the plate 28 isdisplaced in a direction opposite to the direction of rotation of theinterrupter 43, and it can be made to occur later if the plate isangularly displaced in the same direction as the direction of rotationof the interrupter 43.

The switch 48 interrupts the circuit to the light source 38, the sensor34 and amplifier 53, and it may comprise a component of the mainignition switch, as described hereinbefore. Since the light source 38 islocated exteriorly of the distributor casing 12, the heat developed bysuch source whenever it is energized is readily dissipated and does not,therefore, influence the operating characteristics of the sensor 34.Accordingly, the source 38 in association with the light conductor 40may be described as providing a cold light, and not only does it removethe heat source from proximity to the sensor, but it results in thelight having a very good reliability over a long life and also resultsin sharper transitions between the on-off conditions of the transistorbecause peak or maximum light is always available. As respects thedissipation of heat, the mounting block 32 and support 35 may both beformed of aluminum, as indicated, for rapid dissipation of heat 'fromthe area of the sensor. Although indicated hereinbefore that theinterrupter 43 also may be formed of aluminum, it is contemplated thatthe rotor 26 and interrupter can be made integral; and in such case anopaque insulating material would be used for fabrication thereof.

The extreme accuracy in voltage development resulting from theelectro-optical interrupter system of this invention permits the gapdefined by each of the sparking devices 21 to be greater than inconventional systems which results in more efiicient burning of theengine fuel and the development of greater engine horsepower. Further,such accuracy permits the use of a transformer 17 that develops a highersecondary voltage than transformers otherwise employed which results ina hotter spark, and use of such a higher voltage transformer is enabledbecause the on-ofI control of the ignition spark is consistentlymaintained over the entire operating range of the engine.

While in the foregoing specification an embodiment of the invention hasbeen described in considerable detail for purposes of making a completedisclosure thereof, it will be apparent to those skilled in the art thatnumerous changes may be made in such details without departing from thespirit and principles of the invention.

What is claimed is:

1. In an ignition system for internal combustion engines and the likeand which ignition system includes a distributor having a casing and ashaft extending thereinto which is adapted to be rotatably driven bysuch engine, an interrupter system for developing a pulsating currenteffective to energize the ignition system and comprising a sensormounted within said casing and being responsive to the receipt ofradiant energy, a source of radiant energy located remotely from saidsensor, a ngitudinally extending energy conductor for transmitting suchradiant energy from one end to the other and at one such end terminatingadjacent said source of energy and at its other end terminating a spaceddistance from said sensor, a rotatable interrupter located within saidcasing and being interposed between said sensor and adjacent end of saidconductor and being provided with a group of angularly spacedenergy-transmitting areas and a group of angularly spacedenergy-obstructing areas alternately related with saidenergy-transmitting areas, said group of energy-transmitting areas beingeffective to permit the transmission of radiant energy from saidconductor to said sensor and said group of energy-obstructing areasbeing effective to prevent such transmission of radiant energy, saidinterrupter being rotatably driven by said shaft to successively advancein turn each of said energytransmitting areas into alignment with saidsensor and adjacent end of said conductor in timed relation with therotational movement of said shaft, a timing plate located within saidcasing and being displaceable to alter the timing of the distributor andignition system, said sensor and said conductor being supported by saidplate so as to move therewith during any such displacements thereof, anda switching circuit responsive to said sensor and being operative toselectively energize and de-energize the ignition system in accordancewith the condition of said sensor, said source of radiant energy being alight source comprising an electrical lamp, said sensor being aphotosensitive device, and said energy conductor being a light conductorhaving a contoured end portion adjacent said lamp and generallyconformed thereto and being in substantially contiguous relationtherewith.

2. In an ignition system for internal combustion engines and the likeand which ignition system includes a distributor having a casing and ashaft extending thereinto which is adapted to be rotatably driven bysuch engine, an interrupter system for developing a pulsating currenteffective to energize the ignition system and comprising a sensormounted within said casing and being responsive to the receipt ofradiant energy, a source of radiant energy located remotely from saidsensor, a lon gitudinally extending energy conductor for transmittingsuch radiant energy from one end to the other and at one such endterminating adjacent said source of energy and at its other endterminating a spaced distance from said sensor, a rotatable interrupterlocated within said casing and being interposed between said sensor andadjacent end of said conductor and being provided with a group ofangularly spaced energy-transmitting areas and a group of angularlyspaced energy-obstructing areas alternately related with saidenergy-transmitting areas, said group of energy-transmitting areas beingeffective to permit the transmission of radiant energy from saidcondoctor to said sensor and said group of energy-obstructing areasbeing effective to prevent such transmission of radiant energy, saidinterrupter being rotatably driven by said shaft to successively advancein turn each of said energy-transmitting areas into alignment with saidsensor and adjacent end of said conductor in timed relation with therotational movement of said shaft, a timing plate located within saidcasing and being displaceable to alter the timing of the distributor andignition system, said sensor and said conductor being supported by saidplate so as to move therewith during any such displacements thereof, anda switching circuit responsive to said sensor and being operative toselectively energize and de-energize the ignition system in accordancewith the condition of said sensor, said source of radiant energy beinglocated exteriorly of said casing, and said energy conductor extendingthrough said casing so as to terminate at one end adjacent said sourceof energy and at its other end a spaced distance from said sensor.

3. The ignition system according to claim 2 in which said source ofradiant energy is a light source, in which said sensor is aphotosensitive device, in which said energy conductor is a lightconductor, and in which said rotatable interrupter comprises asubstantially opaque disc having a plurality of apertures thereindefining the aforesaid energy-transrnitting areas.

4. The ignition system according to claim 3 in which said light sourcecomprises an electric lamp, and in which said energy conductor has acontoured end portion adjacent said lamp and generally conformingthereto and being in substantially contiguous relation therewith.

5. The ignition system according to claim 3 and further including aheat-conductive mounting block secured to said plate and providing asupport for said sensor, said mounting block being effective to transmitheat between said sensor and plate so as to dissipate heat representingtemperature excesses tending to appear at said sensor.

6. The ignition system according to claim 5 and further including asupport block secured to said plate and providing a mounting for saidconductor, said support block having a portion thereof extendingoutwardly through said casing to dissipate heat to the ambientenvironment thereabo-ut.

7. In an ignition system for internal combustion engines and the likeincluding a distributor having a casing and a shaft extending thereintoadapted to be rotatably driven by such engine and an interrupter systemoperative to develop a pulsating current effective to energize theignition system and comprising a photosensitive sensor mounted withinsaid casing and being responsive to the receipt of radiant energy, alight source providing a source of radiant energy, a rotatableinterrupter located within said casing intermediate said sensor andlight source and being provided with a group of angularly spacedenergytr ansmitting areas effective to permit transmission of radlantenergy from said light source to said sensor and further being providedwith a group of angularly spaced energy-obstructing areas alternatelyrelated with said energy-transmitting areas and being effective toprevent such transmission of radiant energy, said interrupter beingrotatably driven by said shaft to successively advance in turn each ofsaid energy-transmitting areas into alignment with said sensor and lightsource in timed relation with the rotational movement of said shaft, atiming plate located within said casing and being displaceable to alterthe timing of the distributor and ignition system and said sensor andlight source being supported by said plate so as to move therewithduring any such displacements thereof, and a switching circuitresponsive to said sensor and being operative to selectively energizeand de-energize the ignition system in accordance with the condition ofsaid sensor, the improvement in which said light source is locatedremotely from said sensor and comprising a longitudinally extendinglight conductor interposed between said sensor and light source fortransmitting radiant energy from one to the other and beingsubstantially continuous from end to end thereof, and support structuresecured to said plate and providing a mounting for said light source andenergy conductor the latter of which terminates at one end inlight-receiving proximity with said light source and at its other end aspaced distance from said sensor to accommodate the interposition ofsaid interrupter therebetween.

8. The ignition system of claim 7 in which said rotat- UNITED STATESPATENTS 2,169,818 8/1939 Scott.

2,337,535 12/1943 Acs 31712 2,725,487 11/1955 Butler et a1. 2502272,984,695 5/1961 Berdine et. a1.

3,163,700 12/1964 Williamson 350-9t 3,235,742 2/ 1966 Peters 250-233LAURENCE M. GOODRIDGE, Primary Elraminer.

US. Cl. X.R. 123-448

